1. Field of the Invention
The invention relates generally to the field of photography, and in particular to a camera viewfinder. More specifically, the invention relates to a camera viewfinder in which a neutral density or other light reducing filter obscures details of a subject viewed through the viewfinder in low light to provide a warning that ambient light is insufficient for a proper daylight exposure.
2. Description of the Prior Art
When taking a picture it is necessary to know not only in what direction to aim the camera but also how much of the subject will be included in the picture. For this reason practically every camera has a viewfinder of some kind.
Typical prior art U.S. Pat. No. 1,255,167, issued Feb. 5, 1918, discloses a viewfinder with a disk that is rotatable to bring respective openings in the disk successively into registration with a front lens of the viewfinder. Some of the openings are covered by different color light retarding materials to change the amount of ambient light that can enter the viewfinder through the front lens, and they have corresponding notations indicating recommended times of exposure. In operation, the disk is manually rotated until the opening in registration with the front lens makes the subject viewed through the viewfinder appear somewhat faint. Then, the associated time of exposure is selected. If, however, the subject is too faint, the associated time of exposure is too short. A problem with the design is that it may be difficult to aim the camera at the subject and to frame the subject because the view of the subject through the viewfinder is made faint.